Conventionally, in manufacturing a plastic-packaged semiconductor device, a semiconductor chip is fixed to an island portion of a lead frame, and an electrode pad of the semiconductor chip and the inner end portion of an external lead of the lead frame are connected by means of a metallic thin wire, the foregoing chip, island portion and the inner end portion of the external lead are sealed with a sealing plastic, the frame portion of the lead frame is cut off and removed and, thereafter, the external lead laterally protruding from the plastic material is bent into a form suitable for being mounted to the circuit substrate.
By the way, when the semiconductor device is manufactured, after packaged as described above, it is necessary to carry out the test on electrical characteristics. This test is carried out by fitting the semiconductor device to a measuring jig and making the measuring terminal of a testing machine contact the external lead.
According to a conventional manufacturing method, since the external lead is already formed at the time of this test, during handling, one can often touch the external lead, or the external lead can often come in contact with other members causing the external lead to be deformed by bending or the like. Such deformation of the external lead causes it to unexcellently come in contact with the measuring terminal of the testing machine thus making an exact characteristic test difficult to carry out. Further, according to the conventional manufacturing method, since the external lead is already formed at the time of the characteristic test, it is not possible to allow for a large contact area between the measuring terminal and the external lead when it is fitted to the measuring jig, which can readily cause the unexcellent electric contact.